Automotive motor-compressor assembly

ABSTRACT

There is described an automotive motor-compressor assembly ( 1 ) having an electric motor ( 2 ); a compressor ( 3 ) through which a work fluid flows, and having a housing ( 5 ) and an impeller ( 6 ); and connecting means ( 4 ) for releasably fixing the compressor ( 3 ) to the motor ( 2 ), and having a first connecting member ( 10 ) defining a locating surface ( 10   a ) for a connecting portion ( 5   a ) of the housing ( 5 ), and a second connecting member ( 11 ) defining at least one guide surface ( 16 ) for guiding the work fluid inside the housing ( 5 ). (Attached drawing)

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an automotive motor-compressor assembly, in particular for supplying compressed air to fuel-cell systems.

2. Description of Related Art

Automotive motor-compressor assemblies are known which substantially comprise an electric motor; and a centrifugal compressor having a housing fixed to and supported by the electric motor housing, and one or more impellers connected to an output shaft of the motor. More specifically, at one axial end, the electric motor housing has a connecting flange, an outer circumferential surface of which supports and is fitted with the compressor housing.

More specifically, the compressor housing defines an intake at the opposite axial end to the connecting flange, and a volute supply manifold with the flange. The impeller comprises a number of blades fitted to a portion of the output shaft of the electric motor projecting inside the compressor housing.

In a normal operating cycle, air flows from the intake to the supply manifold along a path defined by the inner contour of the compressor housing and by the outer contour of the impeller rotated by the electric motor shaft.

The outer circumferential surface of the connecting flange provides for locating the compressor housing, so the connecting flange involves a relatively high degree of dimensional precision to reduce the gap between the inner contour of the housing and the outer contour of the impeller, and so enhance the overall efficiency of the compressor.

The circular surface, facing the compressor housing, of the connecting flange also provides for guiding the air supply, so that each compressor size calls for a connecting flange of specific shape and size.

When frequent changes are made to the size of the turboblowers fitted to the same type of electric motor, either for test reasons or to permit a certain amount of flexibility in the equipment of different types of vehicles, the above motor-compressor assembly configuration calls for changing the entire connecting flange, which involves complex machining work, especially in view of the close dimensional tolerances of the circumferential surface by which the compressor is located.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an automotive motor-compressor assembly designed to eliminate the aforementioned drawback typically associated with known motor-compressor assemblies.

According to the present invention, there is provided an automotive motor-compressor assembly comprising:

-   -   an electric motor;     -   a compressor through which a work fluid flows, and having a         housing and an impeller; and     -   connecting means for releasably fixing said compressor to said         motor, and comprising at least a first connecting member         defining a locating surface for a connecting portion of said         housing;         characterized in that said connecting means comprise a second         connecting member defining at least one guide surface for         guiding the work fluid inside the housing.

For a clearer understanding of the present invention, a preferred non-limiting embodiment of a motor-compressor assembly will be described by way of example with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partly sectioned side view of the motor compressor assembly.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Number 1 in the accompanying drawing indicates as a whole an automotive motor-compressor assembly, in particular for supplying compressed air to fuel-cell systems.

Assembly 1 has an axis A, and substantially comprises a known electric motor 2 illustrated only insofar as necessary for a clear understanding of the present invention; a compressor 3—in the example shown, a centrifugal compressor; and connecting means 4 for connecting electric motor 2 and compressor 3.

More specifically, of electric motor 2 are shown only a casing 2 a, and an output shaft 7 extending partly inside casing 2 a and partly outwards from one side of casing 2 a.

Compressor 3 comprises a housing 5; and an impeller 6 having a number of blades 12 fixed releasably to the portion of output shaft 7 projecting from casing 2 a of electric motor 2. Housing 5 defines a through axial cavity, and comprises an axial end portion 5 a fixed by connecting means 4 to casing 2 a of electric motor 2; an opposite axial end portion 5 b defining an intake; and an intermediate portion 5 c defining a compression conduit 8 with impeller 6, and a radially outer compressed-air supply manifold 9.

More specifically, axial end portion 5 b has the smallest diameter, and is connected to end portion 5 a, defining the largest diameter, by successive sections varying in diameter and including a radial first portion 5 e, a volute-shaped second portion 5 f, and a radial third portion 5 g.

Supply manifold 9 is therefore defined by a radial initial portion 19 defined between radial portion 5 e of intermediate portion 5 c and connecting means 4 (as described in more detail later on), and by a volute-shaped final portion 20 defined entirely by portion 5 f of intermediate portion 5 c.

Connecting means 4 comprise a first plate 10 fixed coaxially to casing 2 a of motor 2, on the side from which shaft 7 projects, and having an outer circumferential surface 10 a for locating end portion 5 a; and a second plate 11 retained coaxially with casing 2 a, located on the opposite side of plate 10 to electric motor 2, and defining, with intermediate portion 5 c of housing 5, initial portion 19 of supply manifold 9.

More specifically, plate 10 is connected to casing 2 a by releasable fastening means defined, in the example shown, by screws 21, the heads of which are housed inside respective dead seats 18 formed in plate 11. Plate 11 therefore also provides for preventing the drag induced by screws 21 from interfering with the compressed-air flow.

Plate 11 is sandwiched axially between plate 10 and housing 5, and preferably comprises a number of air-guide blades 25. More specifically, housing 5 is fixed at end portion 5 a to the radially outermost portion of plate 10 by means of releasable fastening means defined, in the example shown, by bolts 22, and cooperates, by means of a shoulder formed in volute-shaped portion 5 f, with plate 11 to keep it in axial contact with plate 10. A sealing ring 26 is interposed between said shoulder and plate 11 to fluidtight seal initial portion 19 of supply manifold 9.

At assembly, end portion 5 a of housing 5 is fitted in rotary manner to circumferential surface 10 a of plate 10, and is locked angularly to plate 10 by bolts 22.

More specifically, the radially outermost portion of plate 10 is gripped axially, by means of bolts 22, between radial portion 5 g of housing 5 and two half-ring-shaped stop members 24.

Both plates 10, 11 have an axial hole through which to insert shaft 7 projecting from electric motor 2, and both are centred on a lateral collar 23 of electric motor 2.

As shown clearly in the attached drawing, portion 19 of supply manifold 9 is defined between radial portion 5 e of housing 5 and a surface 16 of plate 11, which is opposite the surface contacting plate 10 and is provided with blades 25.

The advantages of motor-compressor assembly 1 according to the present invention will be clear from the foregoing description.

In particular, by simply modifying plate 11, electric motor 2 can be fitted with impellers 6 and housings 5 of different shapes and sizes, without having to remake plates 10, which are dimensionally much more precise and therefore more expensive.

Moreover, fastening housing 5 to electric motor by means of bolts 22 and stop members 24 leaves housing 5 free to rotate about axis A of electric motor 2. Once, the desired angular position is reached, bolts 22 are tightened, thus simplifying the fastening of housing 5 to electric motor 2.

Clearly, changes may be made to motor-compressor assembly 1 as described and illustrated herein without, however, departing from the scope of the accompanying Claims. 

1) An automotive motor-compressor assembly (1) comprising: an electric motor (2); at least one compressor (3) through which a work fluid flows, and having a housing (5) and an impeller (6); and connecting means (4) for releasably fixing said compressor (3) to said motor (2), and comprising at least a first connecting member (10) defining a locating surface (10 a) for a connecting portion (5 a) of said housing (5); Wherein said connecting means (4) comprise a second connecting member (11) defining at least one guide surface (16) for guiding the work fluid inside the housing (5): 2) A motor-compressor assembly as claimed in claim 1, characterized in that said second connecting member (11) is sandwiched axially between said first connecting member (10) and said housing (5). 3) A motor-compressor assembly as claimed in claim 2, characterized by comprising releasable first fastening means (21) for fastening said first connecting member (10) to said motor (2); said second connecting member (11) defining at least one seat (18) for a respective projecting portion of said releasable first fastening means (21). 4) A motor-compressor assembly as claimed in claim 1, characterized in that said connecting portion (5 a) of said housing (5) is fitted in rotary manner to said locating surface (10 a) of said first connecting member (10); second fastening means (22) being provided to lock said housing (5) to said first connecting member (10) in the desired angular position. 5) A motor-compressor assembly as claimed in claim 1, characterized in that said second connecting member (11) has blades (25). 